The present disclosure relates to a traction apparatus and a traction force control method of a traction apparatus that is used for traction that is performed in manual therapeutics, orthopedics and the like.
As a conventional traction apparatus of this type, there has been proposed a sitting traction apparatus that includes a sling device for slinging up the underarms of a patient and a seat portion that has a fixture for fixing the thighs, and by hoisting the seat portion (upper half of the patient's body) vertically, treats the lumbar and the like (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2003-88540).
Also, as a conventional traction apparatus, there has been proposed a traction apparatus that has a load cell which detects traction force, and detects the traction force so as to use the detection signal for drive control of a motor that is a drive source of the traction force (for example, refer to Japanese Unexamined Patent Application, First Publication No. S59-118156).
However, although the traction apparatus disclosed in Japanese Unexamined Patent Application, First Publication No. 2003-88540 is an apparatus that hoists the upper half of a patient's body by winding up a rope with a motor, there is no specific disclosure regarding the traction control of the motor.
The traction apparatus that is disclosed in Japanese Unexamined Patent Application, First Publication No. S59-118156 is constituted so as to control the traction force with feedback control by detecting traction force with the load cell. In the feedback control, a time lag occurs due to the response time of the load cell as a traction force sensor, the delay time of the feedback circuit, and the like. Accordingly, in such a traction apparatus as shown in FIG. 7, there is the problem that at time ti when the detection value that is detected by the load cell has reached a set traction force (target value) F0, the traction force that is actually applied to the body to be pulled (actual value) temporarily leads to over-traction.
In order to reduce this over-traction, as shown in FIG. 8, it has been conceived to perform feedback control while the traction apparatus increasing the traction force intermittently and gradually. In this case, the traction apparatus first pulls with a traction force of for example approximately 1/7th of the set traction force F0 and maintains that traction force. Next, the traction apparatus gradually raises the traction force to approximately 2/7th of the set traction force F0 at the point of the detection value from the load cell having stabilized, and maintains that traction force. After that, the transaction apparatus again gradually raises the transaction force at the point of the detection value from the load cell having stabilized. The traction apparatus repeats this control until finally pulling the body to be pulled with the set traction force F0. With this kind of feedback control, as shown in FIG. 8, the error between the load cell detection value and the actual traction force (actual value) becomes small, and an over-traction force is prevented from being applied to the body to be pulled. However, with this method, the problem arises that it takes time until reaching the set traction force F0 that is the target value. Also, in the case where the body to be pulled is a human body, there is also the problem that the sense of use is uncomfortable since the traction force changes in small increments.